If you follow Microsoft closely, the face of Qi Lu will be very familiar. He is a fixture of the company’s conferences through his role as Executive Vice President. Simply put, he has been among the most important Microsoft executives in recent years. That’s why it was a major bomb when the company announced Lu will be leaving the company.

Lu has been in charge of the Applications and Service Group, which covers Cortana, Office and Bing. Those two services are, of course, hugely important to Microsoft’s move back to a software-based cloud company.

However, in the wake of his departure, his team will be reorganized and split into separate units. Microsoft CEO, Satya Nadella, sent an email to employees to inform them of the reshuffle.

Replacements

Needless to say, this is a surprising departure. Nadella confirmed that Lu has left for personal medical reasons and is not going to another company or leaving after a breakdown in relationships. The injury is thought to be related to a bike accident, so he could return once recovered.

Indeed, he will continue to act as a personal advisor to Nadella. This is a role he also serves for company founder Bill Gates, and will continue to do so.

Qi Lu has been with Microsoft since 2008. He was a major coup from the company, coming from internet giant Yahoo. He was first drafted in to run Microsoft’s Online Services unit. He will be replaced as Cortana and Bing head by Executive Vice President Harry Shum. Office will now be a separate business under the guidance of Rajesh Jha.

Here is the full email from Satya Nadella:

From: Satya Nadella

Sent: Thursday, September 29, 2016 6:01 AM

Subject: Senior Leadership Team Update

Today, I want to share key senior leadership changes.

First, my friend and colleague Qi Lu has made a difficult and very personal decision to leave Microsoft to focus all his time on recovering from health conditions caused by a prior injury. Once Qi recovers, he will continue to serve as a personal advisor to Bill Gates and me. I wish Qi a full and fast recovery in the coming months, and want to thank him for all he has done for Microsoft.

Over the years, I’ve worked closely with Qi – first as an engineering leader within Bing, later as fellow members of the SLT, and most recently as he led ASG to new heights. The groundbreaking work Qi led during his eight years resulted in many product advances and built the foundation for future innovation across Microsoft. Qi exemplifies what it means to have a deep sense of mission, purpose and authenticity in everything one does. His greatest impact is the people he has inspired. I count myself among them.

As we look ahead, this week at Ignite I focused my keynote on democratizing AI for every person and every organization on the planet. We are on the cusp of a paradigm shift in computing that is unlike anything we have seen in decades. This will lead to artificial intelligence (AI) being infused broadly into our computing platforms and experiences. Advanced algorithms, hyper-scale compute capacity, and the ability to work across massive data sets are what enable us to drive this change in everything we do for customers.

To accelerate this vision, I have asked Harry Shum to lead the Microsoft AI and Research Group, bringing together for the first time our world-class research organization alongside all our AI product efforts. David Ku and the Information Platform Group along with Derrick Connell and the Bing and Cortana Engineering Group will now report to Harry. Vijay Mital and the Ambient Computing and Robotics Team will also be joining Harry’s team.

Rajesh Jha will step into the role of leading the Office Product Group reporting directly to me and joining the SLT starting today. Julie Larson-Green and Eran Megiddo will continue in their current and existing charters, reporting to Rajesh. Gurdeep Singh Pall and I have decided this is the right time for him to transition to his next role. Gurdeep will transition the Skype team to Rajesh over the coming weeks.

We have great momentum with Office 365 in both our business results and product innovation and have made dramatic strides in our evolution to offer productivity and communications as a service. We have much to do in support of our ambition to reinvent productivity, and I am counting on this team to move forward with boldness and urgency.

We live in a time when digital technology is impacting, and indeed transforming, every human endeavor and each of our customers. Our mission to empower every person and every organization on the planet to achieve more continues to guide all we do. It is through our mission and activating a growth mindset culture that will enable us to accelerate digital transformation both within our own company and in partnership with our customers.

Finally, I hope you join me for a special Monthly Q&A today at 9:00 a.m. pt. Harry, Rajesh and I look forward to sharing more and taking your questions.

Luke has been writing about all things tech for more than five years. He is following Microsoft closely to bring you the latest news about Windows, Office, Azure, Skype, HoloLens and all the rest of their products.